Calculating tip in your head is very simple. If you live in an area where the sales tax is between 7% and 8.5% it’s extremely easy to calculate in your head. You simply double whatever the sales tax is and you get around 15% of the total bill. If you don’t want to use that method however, there is another simple way to calculate the tip in your head:

1) Suppose your bill is $18.77 and you want to leave a 15% tip. The first thing you want to do is round up or down to the nearest dollar. In this case you round up to $19.00.

2) Next, you move the decimal to the left one space to get $1.90. (This is 10% of the total bill.)

3) Now round $1.90 to the nearest dollar which is $2.00 (Still pretty close to 10%).

4) Divide by 2 to get $1.00. (This is 5% of the total bill. 10% + 5% =15%)

5) Now add $1.00 to $2.00 and you get $3.00 which is approximately 15% of the total bill.

If you used a calculator you would see that $2.82 is exactly 15% so your estimate was only 18 cents off. If you round down on step 3 you might want to add 50-75 cents to your calculation just to make sure you don’t shortchange your server. If you feel ok leaving a little extra always round UP.

NOW, suppose you want to calculate a tip of 20% in your head. That’s even easier!

1) Suppose your bill is $156.22. Again, the first thing you want to do is round to the nearest dollar which gives you $156.00.

2) Again move the decimal place 1 place to the left to get $15.60, 10% of the bill.

3) If you feel comfortable with doubling $15.60 in your head go ahead and double it to get $31.20, 20% of the bill. If not round $15.60 to the nearest dollar which is $16.00.

4) Double $16.00 to get $32.00. This is approximately 20% of the total bill.

If you use a calculator to determine the tip on $156.22 you would get $31.24. Pretty close! If you want to master this technique play with a couple of hypothetical amounts using the guidelines outlined above (don’t forget to pad the total if you round down on step 3) until you get the hang of it.

submitted by Emily Condit